Thanks so much Otto, appreciate it!
Arch F Owens
Inventory Manager
Bub Enterprises
arch@bubent.com
Phone 530-477-7490 X 217
Fax 530-477-7489
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From: Askotto@aol.com [mailto:Askotto@aol.com]
Sent: Wednesday, May 03, 2006 10:31 AM
To: arch@bubent.com
Subject: Re: Spark plugs 101
Hi Arch
The heat range refers to the length of the center electrode. Longer center
electrodes are hotter because it is sticking out in the flame farther and
the length to the heat sink, the head, is farther. Hot plugs are for street
driving where the plug must contend with varying RPM ranges from idle to
cruise. "Racing" plugs are colder, shorter center electrode, because they
don't have to deal with slow speed driving which can foul a cold plug.
Racing engines run at high RPM under full throttle so fouling isn't a
problem.
The hot setup is run as cool a plug as you can without fouling it. This
takes plug readings after a full throttle "cold cut" run where you kill the
engine immediately at the end of the run, pop it in neutral and coast down
dead. DO NOT IDLE DOWN or engine brake! You immediately pull the plugs and
closely examine the color of the porcelain insulator. You want very light
tan to light gray. If it's white, you're way to hot. If it's dark verging on
black, you're way to cold. It's a hit and miss deal with jetting entering in
the equation. The jetting must be perfect to make accurate plug readings.
We have special flash lights with a magnifying glass to check the heat
ranges properly. Summit and others carry them.
Running too cold will foul plugs and too hot can actually cause detonation
and you can actually melt the electrodes, especially with Nitro or N.O.S.
Get about 3 heat ranges and start cold.
Have fun!
Otto
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